A Twist in Complex Oxides

The recent realisation of freestanding membranes of complex transition metal oxides has enabled twistronics in highly correlated systems. Our research has demonstrated that by stacking freestanding ferroelectric perovskite layers with regulated twist angles, we can customize chiral topological nanostructures. This customization is dictated by the lateral strain modulation that comes with the twisting and in BaTiO3 renders an unusual pattern of polarization ferroelectric vortices and antivortices that arises from the flexoelectric coupling of polarization to strain gradients. This discovery opens up possibilities for the creation of two-dimensional, high-density vortex crystals, paving the way for the exploration of new physical effects and functionalities. Additionally, we have explored the properties of freestanding layers of BaTiO3 as high-k dielectrics in MoS2 FET devices and phototransistors.
[1] G. Sanchez-Santolino et al., Nature, 626, 529–534 (2024)
[2] Thomas Pucher et al. Adv. Funct. Mater., 2409447, (2024)
[2] S, Puebla et al Nano Lett., 22, 18, 7457–7466 (2022)